The present invention relates to the finishing of textile fabric webs by a shrinkage treatment and, more particularly, to such a shrink finishing system of the type wherein a textile fabric web travels from a fabric intake unit to a fabric wetting unit, therefrom to a fabric stretching unit for producing a corresponding reduction in fabric widthwise dimension, therefrom to a compressive shrinking unit for lengthwise fabric shrinkage, and therefrom to a fabric drying unit.
In the shrink finishing treatment of textile fabric webs in shrink finishing systems of the aforementioned type, several criteria should be observed. The fabric web should be wetted with a predetermined moisture content, including a finishing agent, e.g. a lubricating agent, in advance of shrink treatment. The fabric web should also be reduced in its widthwise dimension to a desired finished width. Likewise, the fabric web should be shrunk lengthwise to a predetermined degree. After drying of the shrunk fabric, a predetermined moisture content should remain in the fabric web. The observance of predetermined shrinkage values in shrink finishing of fabric webs is necessary to provide uniform shrinkage properties in compliance with standards suitable for the garment fabrication industry and also to provide desired wearing and ease-of-care properties for articles of clothing manufactured from the fabric web. The above-mentioned parameters apply basically to the finishing of both woven and knitted fabric webs. However, the aforementioned type of shrink-finishing systems to which the present invention relates are preferably utilized for the treatment of woven fabrics.
Heretofore, in the operation and control of a shrink finishing system of the aforementioned type, an untreated fabric web to be shrink finished is initially subjected to a wash test prior to treatment in the shrink finishing system. From the wash test, a percentage contraction of the fabric in its lengthwise, i.e. warpwise direction, which may be designated as EK, is determined and, likewise, a percentage contraction of the fabric web in its widthwise, i.e. weftwise direction, which may be designated as ES, is also determined. A garment manufacturer or other purchaser of the fabric web may specify that the fabric web as delivered to the purchaser must have a predetermined percentage residual warpwise shrinkage, designated as RK, and a predetermined percentage residual weftwise shrinkage, designated RS. Accordingly, the fabric web in such cases must be subjected to a shrink finishing treatment to shrink the fabric web lengthwise by a percentage amount, designated V, equal to the difference between the warpwise test shrinkage EK and the desired residual shrinkage RK, i.e., V (%) equals EK minus RK. Similarly, since the residual weftwise shrinkage corresponds to a certain finished width, designated as B, of the fabric web after the finishing treatment, the system must be operated such that the fabric web after treatment has a finished width equivalent to the dimensional value B.
The residual warpwise and weftwise percentage shrinkage values should of course not exceed maximum allowable tolerances either in excess of or less than the predetermined desired residual shrinkage values. As will be understood, if the residual shrinkage values are too great, the garment or other article produced from the fabric web will experience a greater than desirable shrinkage when ultimately washed, which of course is undesirable to the ultimate purchaser. On the other hand, if the residual shrinkage values are too small, the fabric web has been excessively shrunk resulting in an unnecessary effective loss of fabric.
To achieve an optimal shrink finishing treatment of any given type of fabric web utilizing a shrink finishing system of the aforementioned type, it is therefore necessary, as aforementioned, to establish and conform to a predetermined desired initial moisture content in the fabric web imparted by the wetting unit, a predetermined desired longitudinal tensioning of the fabric web by the elongation unit, a predetermined shrinkage compression of the fabric web by the shrinking unit, and a predetermined final moisture content of the fabric web after drying by the drying unit. Additionally, a predetermined traveling speed V, e.g. in meters per minute, should be established, such speed being determined by the prevailing fabric contact pressure and residence time of the fabric web in the shrinking unit. Conventionally, adherence to the above-mentioned predetermined values has been achieved by manually setting adjustable controls in the shrink finishing system, frequently monitoring actual fabric shrinkage by means of measuring marks placed initially on the untreated fabric, and making manual correcting adjustments as necessary. As will be recognized, this method of manual setting, monitoring and correction is highly service-intensive, especially inasmuch as a modification of one system control may influence other aspects of the treatment system. For example, a modification of the degree of fabric elongation to adjust the finished widthwise dimension of the fabric necessarily also affects the lengthwise shrinkage of the fabric web so that the settings controlling the warpwise fabric web shrinkage must also be adjusted.